Figure 2: The captured images of the tooth were quantitatively analyzed with the QLF software. 1A depicts the selected lesion of interest. 1B the software selects sound area of the tooth structure not affected by caries and simulates sound enamel in the actual area of demineralization by using fluorescent radiance along the line of the lesion shown in 1C. 1D depicts the loss of fluorescent intensity in the lesion calculated by the difference in fluorescent radiance between the simulated sound area and the actual carious area and is expressed as a percentage of that of sound enamel.